1. Field of the Invention
The present invention relates to a noise filter which is detachably mounted on (i.e., which is attached to, and detached from) a cable such as a data transfer line or the like.
2. Description of the Related Art
As a conventional noise filter which is detachably mounted on a cable such as a data transfer line or the like, there has hitherto been know one as disclosed in Japanese Published Unexamined Utility Model Registration Application No. 39997/1988. Namely, the noise filter comprises: a magnetic core which is made up of a pair of magnetic core members (or elements) of ferrite or the like such that, when the pair of magnetic core members are coupled (or closed) together on their coupling surfaces, a closed magnetic path is formed and an opening for inserting therethrough a cable is also formed between the magnetic core members; and an electrically insulating case which is made up of a pair of electrically insulating case members (or elements) for containing therein the pair of magnetic core members. When the pair of electrically insulating case members are closed together, the pair of magnetic core members are coupled together on their coupling surfaces.
As described above, in the conventional noise filter, the pair of magnetic core members are contained inside the respective electrically insulating case members, and the external surfaces of the magnetic cores are thus covered by the electrically insulating case. However, since the dented portions of the pair of magnetic core members which form the opening for inserting therethrough the cable are exposed to the outside, there is the following disadvantage. Namely, when the noise filter is attached to, or detached from, the cable, or when the noise filter is allowed to slide on the cable after it has been attached thereto, there is a possibility that the cladding of the cable (or a cable sheath) is damaged by the corner edges of the dented portions of the magnetic core members.
The present invention has an object of providing a noise filter which is free from the above-described disadvantage.